1. Field of the Invention.
The present invention relates to methods of modifying the structural integrity of subterranean earth situs, to methods of strengthening and improving the load-bearing capacity of subterranean earth situs and to methods of installing structural elements in subterranean earth situs.
2. Description of the Prior Art.
A variety of methods for improving the strength and reducing the permeability of subterranean earth situs have been developed heretofore. Typically, the soil in the situs is loosened and a solidifying agent is admixed therewith, in situ. This is most commonly carried out by drilling an auger-type tool into the situs to loosen the soil and pumping the solidifying agent into the soil through the shaft of the tool. The solidifying agent is typically admixed with the soil by the mechanical action of mixing paddles attached to the tool or the auger flight upon rotation of the tool. The tool is then withdrawn from the situs with or without excavating soil therefrom. The solidifying agent/soil admixture is allowed to harden into a solidified mass. If desired, a structural element can be installed in the situs before the solidifying agent/soil admixture hardens. The resulting element and/or solidified mass can be used to support roadways, bridges, piers, buildings and the like.
Although the methods developed heretofore are effective in many applications, the mechanical action of mixing paddles or the auger flight is not always sufficient to uniformly admix the solidifying agent with the soil. The resultant admixture is slow in setting up and often has poor structural properties. Solidifying agent/soil admixtures having nonuniform consistencies are difficult to work with.
Furthermore, in most of the methods developed heretofore, the strength and load-bearing capacity of the pile and/or solidified soil cannot be determined until after the solidifying agent/soil admixture hardens and load capacity tests are carried out thereon. There is no way to accurately determine the amount of energy required to achieve a sufficient mix. In order to allow for variations in the consistency of the soil from point to point within the situs, the overall extent of solidification carried out is often more than necessary resulting in a waste of labor and materials.
By the present invention, a method of modifying the structural integrity of material in a subterranean earth situs is provided. In accordance with the method, the structural integrity of material in the situs can be either decreased or increased. The method is particularly suitable for increasing the load-bearing capacity of a subterranean earth situs and installing structural elements such as piles, piers and tension anchors therein. A very uniform admixture of a modifying agent and the material in the situs is achieved. The load-bearing capacity of the material in the situs can be determined before and as the method is carried out allowing the overall extent of modification from point to point within the situs to be accurately controlled.